Search results for "Larva"
showing 10 items of 632 documents
Insect Immune Evasion by Dauer and Nondauer Entomopathogenic Nematodes
2021
The immune response of animals, including insects, is overcome by some parasites. For example, dauer larvae (DL) of the obligate entomopathogenic nematodes (EPNs) Heterorhabditis and Steinernema can invade insects, evade their defenses, and cause death. Although DL were long assumed to be the only infective stage of nematodes, recent reports suggest that L2-L3 larvae of facultative EPNs are also capable of killing insects. There are no studies, to our knowledge, about the role of nonimmunological barriers (the exoskeleton and its openings) in avoiding infection by DL and L2-L3 larvae, or whether these larval stages evade the host immune system in the same way. The objective of this study wa…
Effects of the ingestion ofSerratula tinctoria extracts, a plant containing phytoecdysteroids, on the development of the vineyard pestLobesia botrana…
1997
We describe here the effects of extracts from Serratula tinctoria, a plant producing phytoecdysteroids, on the growth and development of Lobesia botrana, an economically important pest in vineyards. Leaves, hairy roots, or semi-purified (by Sep-Pak procedure) methanolic extracts from this plant were incorporated into an artificial diet given to insects. Larval growth, mortality, weight, and sex-ratio were investigated, as well as sterol and ecdysteroid contents. Experimental diets induced an important mortality in the first, second, and third larval instars, but also in pupae. As males appeared more sensitive to extracts, sex ratio was significantly modified on experimental diets (particula…
Potential of the Bacillus thuringiensis Toxin Reservoir for the Control of Lobesia botrana (Lepidoptera: Tortricidae), a Major Pest of Grape Plants▿
2006
ABSTRACT The potential of Bacillus thuringiensis Cry proteins to control the grape pest Lobesia botrana was explored by testing first-instar larvae with Cry proteins belonging to the Cry1, Cry2, and Cry9 groups selected for their documented activities against Lepidoptera. Cry9Ca, a toxin from B. thuringiensis , was the protein most toxic to L. botrana larvae, followed in decreasing order by Cry2Ab, Cry1Ab, Cry2Aa, and Cry1Ia7, with 50% lethal concentration values of 0.09, 0.1, 1.4, 3.2, and 8.5 μg/ml of diet, respectively. In contrast, Cry1Fa and Cry1JA were not active at the assayed concentration (100 μg/ml). In vitro binding and competition experiments showed that none of the toxins teste…
PGal4 excision reveals the pleiotropic effects of Voila, a Drosophila locus that affects development and courtship behaviour
2001
0016-6723 (Print) Journal Article Research Support, Non-U.S. Gov't; In Drosophila melanogaster, the PGal4 transposon inserted at the chromosomal site 86E1-2 is associated with the Voila1 allele that causes multiple phenotypes. Homozygous Voila1/1 flies rarely reach adulthood and heterozygous Voila1/+ adult males display strong homosexual courtship behaviour. Both normal behavioural and developmental phenotypes were rescued by remobilizing the PGal4 element. Yet, the rescue of heterosexual courtship and of adult viability did not occur in the same strains, indicating that these defects have different genetic origins. Furthermore, many strains showed a partial rescue of both characters. Molec…
Signals from the deep-sea: Genetic structure, morphometric analysis, and ecological implications of Cyclothone braueri (Pisces, Gonostomatidae) early…
2020
Abstract Cyclothone braueri (Stomiiformes, Gonostomatidae) is a widely distributed fish inhabiting the mesopelagic zone of marine tropical and temperate waters. Constituting one of the largest biomasses of the ocean, C. braueri is a key element in most of the ecological processes occurring in the twilight layer. We focused on the ecological processes linked to early life stages in relation to marine pelagic environmental drivers (temperature, salinity, food availability and geostrophic currents) considering different regions of the Central Mediterranean Sea. A multivariate morphometric analysis was carried out using six parameters with the aim of discerning different larval morphotypes, whi…
Identificación y caracterización de proteínas de Strongyloides stercoralis de utilidad para el diagnóstico y control de la enfermedad mediante técnic…
2016
El nematodo Strongyloides stercoralis es el principal causante de la estrongiloidiasis humana. Debido a la capacidad del parásito de perpetuar un ciclo autoinfectivo la infección puede prolongarse durante años en el hospedador, dando lugar a una enfermedad crónica en personas inmunocompetentes, mientras que en condiciones de inmunosupresión puede desembocar en cuadros clínicos graves con elevadas tasas de mortalidad. La región de La Safor valenciana ha sido considerada foco endémico de este parásito desde hace más de un siglo, habiéndose diagnosticado cientos de casos desde entonces, suponiendo un problema sanitario en la región. La presente Tesis contribuye a la mejora en el conocimiento p…
Slipper lobsters from Atlantic waters: revision of Scyllarus Fabricius, 1775 (Crustacea: Scyllaridae) using a multiple-evidence approach
2020
L’infraordre Achelata (Crustacea: Decapoda) es caracteritza per la seua manca de pinces al primer parell de pereopodis i per la presència d’una forma larval altament especialitzada, la larva fil·losoma. Tradicionalment, les diferències morfològiques entre els adults i les fil·losomes han dificultat la identificació de les larves de llagosta. En els últims anys, l’ús del codi de barres d’ADN (DNA barcoding en anglès) ens ha permés identificar mostres de plàncton a nivell d’espècie. Aquesta tesi es centra en l’estudi de les espècies de Scyllarinae presents a l’oceà Atlàntic oriental, per a la majoria de les quals la forma larval encara és desconeguda. El material de la tesi inclou una gran qu…
Direct activation of zebrafish neurons by ultrasonic stimulation revealed by whole CNS calcium imaging
2020
Abstract Objective. Ultrasounds (US) use in neural engineering is so far mainly limited to ablation through high intensity focused ultrasound, but interesting preliminary results show that low intensity low frequency ultrasound could be used instead to modulate neural activity. However, the extent of this modulatory ability of US is still unclear, as in in vivo studies it is hard to disentangle the contribution to neural responses of direct activation of the neuron by US stimulation and indirect activation due either to sensory response to mechanical stimulation associated to US, or to propagation of activity from neighboring areas. Here, we aim to show how to separate the three effects and…
High sensitivity of northern pike larvae to UV-B but no UV-photoinduced toxicity of retene
2003
In order to investigate whether increased UV-B radiation is a risk factor, a series of acute laboratory experiments was conducted with larval stages of the northern pike (Esox lucius L.), hatching in Nordic waters in May. Further, a comparative investigation on the acute phototoxicity of retene (7-isopropyl-1-methylphenanthrene), a PAH compound recently revealed to posses UV-B-induced phototoxicity in larval coregonids, was conducted with pike larvae. In semi-static experiment, larvae were pre-exposed to retene (3, 9, 30 and 82 microg/g), with relevant controls, for 24 h and then irradiated for 3 h once a day (two consecutive days) with three UV-B doses (CIE-weighted 1.0, 1.8 or 2.7 kJ/m2 p…
Histopathological responses of newly hatched larvae of whitefish (Coregonus lavaretus s.l.) to UV-B induced toxicity of retene
2003
Positively phototactic fish larvae may be exposed to increased ultraviolet-B (UV-B) radiation alone or, potentially and in addition, to polycyclic aromatic hydrocarbons (PAHs) such as retene (7-isopropyl-1-methylphenanthrene) at the egg or larval stages. Suspended and sedimental particulate material near pulp and paper mills may act as sources of retene in chemically contaminated lake areas. In laboratory conditions whitefish larvae were pre-exposed to retene (10, 32 and 100 microg/l), with relevant controls, and irradiated in semi-static tests for 3 h once a day (2 consecutive days) with two UV-B doses (CIE-weighted 2.8 or 5.4 kJ per m(2) per day) or with visible light only. These UV-B dos…